Not just Xcode 26 — re-releasing with an older version of Xcode has the same issue. For users on iOS 12 and below, the app can no longer launch.

The same codebase previously ran fine when uploaded to TestFlight, but after re-uploading it now fails to launch on iOS 12, even though neither the code nor the Xcode version has changed. I suspect a recent change in the App Store Connect backend processing pipeline is the cause.